Vacuum sealing food into a plastic bag and then immersing the bag in hot water, sometimes referred to as “sous vide” cooking, may result in food that has been cooked more uniformly throughout than food prepared by other cooking methods such as sautéing, frying, or grilling. Sous vide cooking may bring all parts of a food item to a safe temperature for consumption without some parts of the food overcooked and other parts undercooked. Food cooked by sous vide methods may have better flavor, texture, or nutritional value than food cooked by other methods.
While immersion cooking of vacuum-sealed food in a hot water bath may produce desirable results, there are disadvantages with methods and equipment used in the past. For example, it may take several hours to cook a food item by sous vide methods, compared to a few minutes for some other methods. It may be preferable to maintain hot water used in sous vide cooking within a narrow temperature range for the entire time needed to cook a food item. For example, some practitioners of sous vide methods suggest that water bath used for immersion cooking should be maintained within ±1° C., while others suggest even narrower limits. Maintaining water temperature within such a narrow range may be difficult to achieve, especially when more than one item is to be cooked, different types or sizes of pots are used for holding hot water, large volumes of water are used for immersion, heat sources respond slowly to set point changes, or water temperature is deliberately changed to cook different kinds of food. Immersion heaters and temperature controllers having sufficient accuracy and capacity for sous vide cooking may be large or expensive and may use control settings and terminology that could be unfamiliar to chefs. When cooking stoves are used for heating water used for immersion cooking, predicting water temperatures from settings for stovetop heating elements may be very difficult and may require extensive trial and error and frequent temperature monitoring. Conventional stoves may not be able to maintain water temperatures within a preferred range.
Cooking time and results may be unpredictable when adapting instructions for one arrangement of equipment to another. Improperly cooked food may represent a substantial financial loss for a commercial kitchen and may expose many diners to a health hazard. Stovetop burners or heating elements being used to heat water may not be available for other cooking tasks while sous vide cooking is underway, so valuable kitchen space and equipment may be tied up for hours. Immersion heaters may have exposed heating surfaces that present a burn hazard to persons near the equipment. A container of hot liquid in a crowded or busy kitchen may represent a safety hazard to persons working near the container, for example spills or contact with hot pots or cooking surfaces. Liquids used for immersion cooking may present other safety hazards. For example, flammable cooking oil may be used instead of water for some sous vide preparations. Any of these problems or disadvantages may multiply when more than one water bath is needed, either for achieving a desired cooking capacity or for simultaneously cooking different food items at different temperatures.